/Engine/Plugins/Editor/ObjectMixer/LightMixer/Source/LightMixer/Public/LightMixerObjectFilter.h
Specify a list of property names corresponding to columns you want to show by default. For example, you can specify "Intensity" and "LightColor" to show only those property columns by default in the UI. Columns not specified will not be shown by default but can be enabled by the user in the UI.
virtual [TSet](API\Runtime\Core\Containers\TSet)< [FName](API\Runtime\Core\UObject\FName) > GetColumnsToShowByDefault() const